NASA rover discovers two distinct speeds of sound on Mars
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NASA’s Perseverance rover discovers that sound travels at two different speeds on Mars, a finding from the first-ever audio recordings on the planet’s surface. High-frequency sounds above 240 hertz move at about 250 meters per second, outpacing the 240 m/s for lower frequencies. The results, published in Nature, come from four hours of audio captured by the rover’s SuperCam microphone.
First Martian Audio
NASA’s Perseverance rover recorded Martian sounds on 19 February 2021, the day after landing, using a microphone on the SuperCam instrument. By its 216th sol, the rover had captured four hours and 40 minutes of audio, including the drone of the Ingenuity helicopter and the crackle of its own laser striking rocks. The acoustic environment proved far quieter than Earth’s, with surface pressure at just 0.6 kilopascals — less than 1% of sea-level pressure — leading researchers to initially suspect a malfunction.
Two Speeds of Sound
Analysis published in Nature on 1 April 2022 showed sound velocity on Mars splits at around 240 hertz. Below that frequency, sound travels at roughly 240 metres per second; above it, at about 250 m/s. This means high-pitched components of a sound arrive ahead of the bass, a phenomenon never observed on Earth. The measurement used Ingenuity’s rotor noise and laser-induced sparks as acoustic sources.
Atmospheric Impact on Acoustics
The divergence stems from the low-pressure, carbon-dioxide-rich atmosphere. Below 240 Hz, CO2 molecules have time to absorb and release acoustic energy, altering the effective heat capacity and slowing the wave. Above that threshold, the molecules cannot relax quickly enough, raising the speed of sound. The effect also causes rapid attenuation of high frequencies, so a human voice on Mars would sound muffled and carry only a few metres.
What's Next
NASA plans to continue acoustic monitoring throughout Perseverance’s mission, with seasonal and diurnal variations expected to provide further insight. It remains unclear how these findings will influence future Mars missions or the design of communication systems for human explorers.
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NASA rover discovers two distinct speeds of sound on Mars
